Protein elongation factor 2 as a target for antifungal and antiparasitic agents

Abstract

Inhibition of protein elongation factor 2 provides a target for identifying potential antifungal and antiparasitic compounds. EF2 inhibitors are useful as therapeutic agents against fungal and parasitic infections.

What is claimed is:  
     
         1 . A method of identifying compounds which selectively inhibit fungal or parasitic protein synthesis by impairing the function of the fungal or parasitic elongation factor 2 (EF2).  
     
     
         2 . EF2 as a specific target for antifungal and antiparasitic agents.  
     
     
         3 . A method for identifying a compound which inhibits EF2 comprising 
 (a) adding a compound to a genetically engineered eukaryotic organism capable of detecting pathogen selective effects on EF2 function, and    (b) determining whether said compound inhibits protein synthesis by assaying growth inhibition.    
     
     
         4 . A method for identifying a compound which selectively inhibits EF2 which comprises 
 (a) constructing fungal or protozoan cells that express a heterologous EF2 from fungal and parasitic pathogens;    (b) inoculating cells into liquid or onto solid growth medium containing test compounds or fermentation extracts; and    (c) quantitating the minimal inhibitory concentration (MIC) of the test compound to completely inhibit growth in liquid or the measurement of an inhibitory zone on a solid substrate.    
     
     
         5 . The method of  claim 4  wherein the cells are inoculated onto a solid growth medium and the MIC of the test compound is the measurement of an inhibitory zone on a solid substrate.  
     
     
         6 . The method of  claim 4  wherein the cells are inoculated into liquid growth medium and the MIC of the test compound is the measurement of complete inhibition of growth in the liquid.  
     
     
         7 . A method for identifying a compound which inhibits EF2 comprising 
 (a) plating a known dilution of cells on the appropriate medium;    (b) contacting said cells with a known dilution of a test compound or natural product extract;    (c) incubating said cells at about 30° C. for about 16 to 24 hours; and    (d) quantitating the percent of growth inhibition specific for loss of EF2 function due to the test compound or natural product extract.    
     
     
         8 . The method of  claim 3  wherein said eukaryotic organism is  Saccharomyces cerevisiae  deleted or mutated for EF2.  
     
     
         9 . A modified  Saccharomyces cerevisiae  cell wherein the cell expresses a heterologous EF2.  
     
     
         10 . A method for identifying compounds having antifungal activity comprising: 
 (a) contacting EF2 or an extract containing EF2 with a known amount of a labeled compound that interacts with EF2;    (b) contacting said EF2 or said extract with a known dilution of a test compound or a natural product extract; and    (c) quantitating the percent inhibition of interaction of said labeled compound induced by said test compound.    
     
     
         11 . The method of  claim 10  which further comprises quantitating the percent inhibition of interaction with a host EF2 of said labeled compound induced by said test compound.  
     
     
         12 . A method for the treatment or prevention of fungal diseases comprising administering to a host a therapeutically or prophylactically effective amount of a compound which inhibits EF2 function of the fungi.  
     
     
         13 . A method for the treatment or prevention of parasitic diseases comprising administering to a host a therapeutically or prophylactically effective amount of a compound which inhibits EF2 function of the parasite.  
     
     
         14 . The method of  claim 12  wherein said fungal disease is caused by Candida, Aspergillus, Cryptococcus, Fusarium, Penicillium or Dermatophytes.  
     
     
         15 . The method of  claim 13  wherein said parasitic disease is caused by Plasmodium, Eimeria, Isospora, Neospora, Toxoplasma, Cryptosporidium, Trypanosoma, Leishmania or Theileria.  
     
     
         16 . The method of  claim 12  wherein said compound impairs fungal EF2 function to a greater extent than host EF2 function.  
     
     
         17 . The method of  claim 13  wherein said compound impairs parasitic EF2 function to a greater extent than host EF2 function.  
     
     
         18 . A composition useful for the prevention or treatment of fungal diseases which comprises an inert carrier and an effective amount of a compound that selectively impairs fungal or parasitic EF2 function.  
     
     
         19 . The composition of  claim 18  wherein said compound which selectively impairs fungal or parasitic EF2 function is sordarin.